Composition for treating the liquid contents of heating and cooling systems



circulates.

' automotive engines.

Patented Jan.v 8, 1935 UNITED STATES PATENT OFFICE COMPOSITION FOR TREATING THE LIQUID CONTENTS OF HEATING AND COOLING SYSTEMS No Drawing.

Application February 5, 1934, Serial No. 709,788

14 Claims. (Cl. 252-5) The present invention relates to an improved composition of matter'intended to be employed for the treatment of the liquid contents of heating and cooling systems such as hot water radiators, hot water boilers, cooling jackets of automotive engines, steam engines and radiators of the hot water type, as well as those employed for the cooling of internal combustion engines on automobiles, airplanes and the like, which may contain antifreeze liquids or solutions.

The particular object of the invention is to provide a composition of matter which may safely be added to the liquid contents of heating and cooling systems without in any way causing any deleterious alterations in the metallic, rubber or other parts of which said systems are composed.

Primarily, the composition is intended to be used in motor cars and airplanes, and the cooling systems of the internal combustion, Diesel or other engines used in connection with such vehicles.

The fundamental principle .upon which the present invention is predicated is that as it becomes necessary to maintain a supply of either water or water plus an antifreeze composition, or antifreeze composition alone, in automobile radiators and cooling systems such as in the jackets surrounding the cylinders of the engines, this automatically brings with it a certain amount of rusting or corrosion which eventually interferes with the proper operation of the engines and the radiators. This corrosion or rusting is particularly noticeable when acids are developed in the water, and it has hitherto been proposed to employ alkaline reacting materials such as sodium carbonate, caustic soda, borax and the like for the purpose of keeping the water alkaline in the hope that this would inhibit the rusting and corrosion.

While it is true that alkali-containing. materials will inhibit the rusting of ferrous metals, such alkaline solutions are, however, highly deleterious to various nonfe'rrous metals which are now in increasing amounts being employed in The present trend is toward. the employment of aluminum cylinder heads,

which are bored out or otherwise provided with hollow jackets through which the cooling water Inasmuch as alkalies violently attack aluminum, it is obvious that such alkaline reacting materials cannot be used with engines having aluminum cylinder heads. Formerly, when brass and bronze were widely used for motor car radiators, a certain amount of alkali in the cooling water did no particular harm, al-

though there was always the possibility of corrosion being set up because of'the conductivity imparted to the cooling water by the dissolving therein of electrolytes. However, if the cooling water can be kept neutral or substantially so, any corrosion due to electrolysis is reduced to the minimum. Acid-reacting cooling water will attack the metal parts of the engine and cooling cylinders and greatly increase the rusting thereof, and will also affect aluminum, while on the other hand an alkaline reacting substance in the cooling water -while comparatively harmless to the iron parts-will rapidly corrode all aluminum parts. Thus there is presented an entirely new problem, toward the solution of which the present invention is directed.

While the composition is primarily intended for use in automobile radiators, it is by no means restricted thereto; thus, for example, it can also be used to keep clean the interior of hot water heating systems, such as the usual hot water boilers, pipes and radiators therewith connected or in hot or cold water supply systems. Such hot water heating systems are commonly employed for the heating of homes and other buildings, and are in widespread use.

An additional use for the present invention resides in keeping clean the water cooling systems of steam engines, turbines, and even the interior of brine pipes in refrigerating and freezing systems.

The composition is likewise adapted to the cleaning of pipe lines, valves and other fittings through which water or aqueous solutions are circulating.

One of the principal functions of the composition is to prevent the adhesion of scale-forming material, as well as to loosen such'scale as may already have been formed.

In the hereunto annexed claims, the term water-containing system is intended to cover all of the above described devices in which water or an aqueous solution is maintained, either for purposes of heating or cooling.

The composition consists of a normally alkaline-reacting phosphate salt-that is, a saltof an acid of phosphorus, plus such other materials as will reduce the alkalinity of this phosphorus acid salt to substantially the point of neutrality, viz., so that the mixture will have a hydrogen ion concentration equivalent to pH*:. This may be accomplished in a number of ways.

For example, one may start with trisodium has been found to be particularly effective consists of the following:

Parts by weight Commercial dry powdered chestnut tannin 50 to 60 Commercial dry powdered cutch tannin 20 to 30 T r i s o d i u in phosphate monohydrate (Na3PO4.H20) 10 to 30 These materials are ground and merely mixed together. A slight variation in the percentage between the ranges given will usually be neces- -sary, as the acidity of the chestnut tannin and cutch tannin varies slightly; but in any event the hydrogen ion concentration of the .mixture should be substantially equivalentto pH7.

The chestnut and cutch tannins mentioned herein are well known articles of commerce, but it may be stated that other tanning agents of a similar type, such as are known to the trade, may be substituted, suitable provisions being made for varying the amounts in accordance with" their variation in acidity.

Other water solublematerials than the tannins may be used, such for example as water soluble gums of the general nature of gum arabic, acacia, karaya gum, or starches and the like, in which case, however, a sufficient amount of some acidreacting substance must be used to bring the composition substantially to the equivalent of pHv. On the other hand, it is also possible to start with an acid-reacting phosphate such as NaH2PO4 or NazHPOi, in which case sufficient alkali is added, such as sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, and the like, to bring the acidity of these acid-reacting phosphate salts to the substantially neutral point, equivalent to pH'z.

The invention is by no means limited to sodium phosphate, as other salts of phosphorus may be used. Such salts are sodium metaphosphate (NaPoa) and sodium pyrophosphate (NazPzOvL The reason for this is that these metaphosphates and pyrophosphates, upon being dissolved in water, slowly hydrolyze, with the eventual formation of ordinary orthophosphate. Irrespective of which phosphate salt is used, the hydrogen ion concentration of the mixture is adjusted, either by the addition of an acid or an alkalias the case may be-to yield a material neutral in reaction.

The composition is usually marketed in the form of a dry mixture, but it may with equal success he sold in the form of a paste, or aqueous suspension or solution.

The material is used by adding it to the water that is to be employed either for heating or cool ing, or by dissolving it in the brine that is used for refrigeration.

The material, because of the fact that it has neither an acid nor an alkaline reaction, will not corrode aluminum, iron, brass, bronze, copper, chromium, or the like. It further will prevent corrosion by water containing oxygen because of the fact that the tannins are oxidizable materials and hence remove the oxygen from the water, thereby removing one of the most powerful corroding influences contained therein. Secondarily, the tannins tend to react with any oxide or hydroxide film that may already have formed on the iron surfaces, with the formation of iron tannates, which prevent further corrosion. The composition itself, because of its neutrality, has but slight softening action on the water, nor is it intended that it so alter the Water. The composition, when dissolved in water or suspended therein, yields a free flowing flocculent sludge that will gradually remove hammer scale, oxides, or any precipitated material or scale, from the iron or aluminum parts of a heating or cooling system; and furthermore will prevent the subsequent adherence to such metallic surfaces of scale, rust, and other encrusting matter. It also tends to remove oil and grease from iron and aluminum surfaces, so that the phosphate contained in the mixture, together with the tanning agents, may have free access to the iron surfaces so that it may react therewith to form inherently rust and oxidation preventing films.

The composition has found particular application in the commercial manufacture of motor cars, during which the engines or cooling systems are tested out upon test blocks, whereupon the cooling water is withdrawn. Under such circumstances, and when pure water is used, the interior of the water jackets and radiators of such engines will become badly rusted during the time the cars are in transit and on the floors of sales agencies, requiring expensive cleaning before the cars are placed into service. If, however, the composition of the present invention is used in the motor during the breaking in or testing of the motor and the solution is subsequently withdrawn, there will remain deposited on the interior surface of the cooling system a rust retarding and oxidation preventing film which obviates all difliculties that are at present encountered in this field.

Another advantage of the present composition resides in the fact that because of the cutting of grease and oil in a heating system, it will pre vent foaming. Thus it may also be employed in boilers or other steam generating or evaporating equipment, so as to prevent undue foaming "tion or suspension placed in a radiator or cooling system already considerably corroded will rapidly tend to remove the corroding material, causing it to become suspended in the water, so that it may then be withdrawn together with the solution, whereupon a fresh solution is placed in the heating or cooling system, thereafter protecting the same from further rusting, oxidation, or corrosion.

As a guide to the approximate calculation of the amount of chestnut tannin and cutch tannin or of alkaline material that should be used,'it may be stated that the commercial types usually contain from 6% to 8% acidity, when calculated as acetic acid. What the true nature of the acidity is has never been satisfactorily determined, but it is probably tannic acid together with other complex organic acids of like nature.

What it is intended to protect by Letters Patent is the following:

l. A composition for preventing incrustation in water-containing systems, which comprises a soluble phosphate and a. water-soluble compound from the group consisting of carbohydrates and tannins, the reaction of the mixture being adjusted to approximate neutrality.

2. A composition for preventing incrustation in water-containing systems, which comprises an alkaline reacting sodium phosphate, a water soluble carbohydrate, and sumcient acid/to yield a mixture that has a. hydrogen ion concentration of approximately PH'I. 3. A composition for preventing incrustation in water-containing systems, which comprises an acid reacting phosphate, a water-soluble carbohydrate, and suflicient alkali to produce a mixture oi a hydrogen ion concentration equivalent to DB1.

4. A composition for preventing incrustation in water-containing systems, which comprises a phosphate of an alkali metal in which all three hydrogen atomsioi the phosphoric acid have been replaced by the alkali metal, and a water-soluble tannin having an acid reaction, suiiicient of said tannin being employed'to yield a final composition having a hydrogen ion concentration sub- 3ostantially equivalent to p111.

5. A composition for preventing incrustation in water-containing systems, which comprises trlsodium phosphate and suflicient commercial tannin to yield a composition having a hydrogen ion concentration substantially equivalent to DB1.

8. A composition for preventing incrustation in water-containing systems, which comprises A in water-con substantiallyto parts of chestnuttannin,

trlsodium phosphate, chestnut tannin and cutch tannin, the two tannins being employed in willcient amounts to neutralise the alkalinity oi the' trisodlum phosphate.v

'l. A composition !or preventing incrustation systems. which comprises mtowpartsoicutchtanninandlotosoparts oi triscdium phosphatemonohydrate.

8. A composition for preventing incrustation in water-containing systems, which comprises trialkali phosphate and a water-soluble tanningagent, the hydrogen ion concentration of the mixture being adjusted to substantially the equivalent oi pH-z.

9. The method of preventing the corrosion of the interior surfaces of water-containing systems which comprises filling the same with a solution oi. a salt of phosphoric acid and a watersoluble organic compound from the group consisting of carbohydrates and tannins, and adlusting the hydrogen ion concentration of the resulting solution to substantially the equivalent of pH-r.

10. The method of preventing the corrosion of the interior surfaces of water-containing systems which comprises dissolving therein a trialkali phosphate and a tannin in such relative amounts that the resultant solution will exhibit a hydrogen ion concentration substantially equivalent 11. The method of preventing the corrosion of the interior surfaces of water-containing systems which comprises dissolving therein trisodium phosphate and a suilicient quantity ofan acid reacting tannin compound to produce a solution having a' hydrogen ion concentration substant a equivalent to pm.

12. The method or preventing the corrosion of the interior suriaces oi water-containing systems which comprises dissolving therein an acid phosphate, a water-soluble carbohydrate, and

sufllcient alkali to reduce the acidity of the re- 

